Shk-based pharmaceutical compositions and methods of manufacturing and using the same

ABSTRACT

Disclosed herein are pharmaceutical compositions having the sequence Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys (SEQ ID NO:1). The disclosed compositions can include an acid or amide at the C-terminus of SEQ ID NO:1 and the polypeptide can be attached to an organic or inorganic chemical entity that has an anionic charge. The polypeptide can be detectably labeled for diagnostic purposes. Methods of manufacturing and using the pharmaceutical compounds are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.14/124,669, filed on Dec. 6, 2013, which is a U.S. national phaseapplication based on International Application No. PCT/US2012/040857,filed on Jun. 5, 2012, which claims priority to U.S. ProvisionalApplication No. 61/493,868 filed on Jun. 6, 2011 and U.S. ProvisionalApplication No. 61/625,578 filed on Apr. 17, 2012, all of which areincorporated by reference in their entirety herein.

STATEMENT OF GOVERNMENT INTEREST

The United States government has rights in the present disclosurepursuant to National Institutes of Health National Institute of Allergyand Infectious Diseases Grants R43AI085691 and NIH R01NS48252.

FIELD OF THE DISCLOSURE

The compositions and methods disclosed herein relate generally to theuse of ShK-based pharmaceutical compositions to treat, prevent and/oralleviate symptoms associated with diseases and disorders in whichmemory T cells play a role, including autoimmune diseases and metabolicdisorders.

SUMMARY OF THE DISCLOSURE

Many immune-related human diseases and metabolic disorders areattributed to the action of memory T cells. Such immune-related diseasesinclude, among others, autoimmune diseases such as multiple sclerosis,type-1 diabetes mellitus, rheumatoid arthritis, and psoriasis. Examplesof metabolic disorders include obesity, Type 2 diabetes,hypercholesterolemia, coronary artery disease, metabolic syndrome,metabolic syndrome X, insulin resistance, hyperlipidemia, lipodystrophy,dyslipidemia, hypertriglyceridemia, glucose intolerance andhypertension.

Two categories of memory T cells are known: central memory T cells(T_(CM)) and effector memory T cells (T_(EM)). Upon activation, T_(EM)cells up-regulate Kv1.3 K⁺ ion channels. The antigen-drivenproliferation of T_(EM) cells is sensitive to Kv1.3 K⁺ ion channelsblockers (Wulff et al., J. Clin. Invest. 111:1703-1713, 2003), and thepolypeptide ShK, originally isolated from the Caribbean sea anemoneStichodactyla helianthus, serves as such a blocker. By blocking Kv1.3channels, ShK suppresses proliferation of T_(EM) cells at picomolarconcentrations.

One embodiment disclosed herein includes a pharmaceutical compositioncomprising an ShK polypeptide having the sequenceArg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys(SEQ ID NO:1; wherein Xaa is Met or Nle).

Another embodiment includes a pharmaceutical composition comprising anShK polypeptide having the formulaArg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(SEQ ID NO:3).

Another embodiment includes a pharmaceutical composition comprising anShK polypeptide having the formulap-phospho-Tyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(ShK-186; SEQ ID NO:2).

Another embodiment includes a pharmaceutical composition comprising anShK polypeptide having the formula L-Cysteinamide,4-phosphono-L-phenylalanyl-2-[2-(2-aminoethoxy)ethoxy]acetyl-L-arginyl-L-seryl-L-cysteinyl-L-isoleucyl-L-α-aspartyl-L-threonyl-L-isoleucyl-L-prolyl-L-lysyl-L-seryl-L-arginyl-L-cysteinyl-L-threohyl-L-alanyl-L-phenylalanyl-L-glutaminyl-L-cysteinyl-L-Lysyl-L-histidyl-L-seryl-L-norleucyl-L-lysyl-L-tyrosyl-L-arginyl-L-leucyl-L-seryl-L-phenylalanyl-L-cysteinyl-L-arginyl-L-lysyl-L-threonyl-L-cysteinylglycyl-L-threonyl-,cyclic (5→37),(14→30),(19→34)-tris(disulfide) (referred to herein asShK-192, CAS Registry Number 1159528-26-3; SEQ ID NO:4), wherein theShK-192 polypeptide is attached to an organic or inorganic chemicalentity that has an anionic charge, and the C-terminus is an acid or anamide.

Another embodiment includes a pharmaceutical composition comprising anShK polypeptide having the formulaTyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(ShK-198; SEQ ID NO:5).

In another embodiment, ShK polypeptides are attached to an organic orinorganic chemical entity that has an anionic charge. In anotherembodiment, the C-terminus is an acid or an amide. In another embodimentthe ShK polypeptides are attached to an organic or inorganic chemicalentity that has an anionic charge and the C-terminus is an acid or anamide.

In another embodiment, one or more chemical entities are attached to theN-terminus of the ShK polypeptide. In another embodiment, the chemicalentity can be attached to the N-terminus of the ShK polypeptide througha linking molecule or linking group. In another embodiment, the chemicalentity is attached to the N-terminus of the ShK polypeptide by anaminoethyloxyethyloxy-acetyl linker.

In another embodiment, chemical entities are selected from the groupconsisting of L-Pmp(OH₂); D-Pmp(OH₂); D-Pmp(OHEt); L-Pmp(Et₂);D-Pmp(Et₂); L-Tyr; L-Tyr(PO₃H₂); L-Phe(p-NH₂); L-Phe(p-CO₂H);L-Aspartate; D-Aspartate; L-Glutamate; and D-Glutamate.

In another embodiment, chemical entity/linker combinations are selectedfrom the group consisting of AEEAc-L-Pmp(OH₂); AEEAc-D-Pmp(OH₂);AEEAc-D-Pmp(OHEt); AEEAc-L-Pmp(Et₂); AEEAc-D-Pmp(Et₂); AEEAc-L-Tyr;AEEAc-L-Tyr(PO₃H₂); AEEAc-L-Phe(p-NH₂); AEEAc-L-Phe(p-CO₂H);AEEAc-L-Aspartate; AEEAc-D-Aspartate; AEEAc-L-Glutamate; andAEEAc-D-Glutamate.

In another embodiment, the ShK polypeptide is provided within thepharmaceutical composition as a pharmaceutically acceptable saltthereof. In another embodiment, the pharmaceutically acceptable salt isan acetate. In another embodiment, the pharmaceutically acceptable saltis potassium acetate or sodium acetate.

In another embodiment, the pharmaceutical composition is provided in anaqueous carrier.

In another embodiment, the pH of the pharmaceutical composition isbetween 5 and 7. In another embodiment, the pH of the pharmaceuticalcomposition is 6.0.

In another embodiment, the pharmaceutical composition further comprisesa surfactant in an amount effective to dissolve the ShK polypeptide inan aqueous carrier. In another embodiment, the surfactant is polysorbate20. In another embodiment, the surfactant is polysorbate 20 at 0.05 w/v%.

In another embodiment, the pharmaceutical composition further comprises10 mM sodium phosphate. In another embodiment, the pharmaceuticalcomposition further comprises 150 mM NaCl.

In another embodiment, the ShK polypeptide is present at an amount from0.01 mg/ml to 500 mg/ml. In additional embodiments, the ShK polypeptidecan be provided in amount of 0.01, 0.1, 0.5, 0.75, 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43,44, 45, 46, 47, 48, 49, 50, 150, 200, 250, 300, 350, 400, 450 or 500mg/ml.

In another embodiment, the ShK polypeptide is obtained from a naturalsource. In another embodiment, the ShK polypeptide is synthetic. Inanother embodiment the ShK polypeptides include a mixture of natural andsynthetic ShK polypeptides.

Embodiments described herein also include lyophilized pharmaceuticalcompositions produced beginning with a composition described herein. Inone embodiment, the lyophilized pharmaceutical composition comprises8-12% acetate content by weight. In another embodiment, the lyophilizedpharmaceutical composition comprises 10-11% acetate content by weight.

In another embodiment of the lyophilized pharmaceutical compositions,the water content of the pharmaceutical composition is less than 5%. Inanother embodiment of the lyophilized pharmaceutical compositions, thewater content is less than 4.0%. In another embodiment of thelyophilized pharmaceutical compositions, the water content is less than3.5%.

In another embodiment the pharmaceutical compositions are provided in apackaging material. In another embodiment, the pharmaceuticalcompositions are formulated for long-term storage. In anotherembodiment, the pharmaceutical compositions are contained in a sterileglass vial and instructed to be stored at −70° C.

In another embodiment, the pharmaceutical compositions are formulatedfor subcutaneous administration. In another embodiment, thepharmaceutical compositions are contained in a sterile syringe.

One embodiment includes a pharmaceutical composition comprising apharmaceutically acceptable salt of an ShK polypeptide having thesequenceArg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys(SEQ ID NO:1; wherein Xaa is Met or Nle); 10 mM sodium phosphate; 150 mMNaCl; and Polysorbate 20 at 0.05 w/v %, wherein the ShK polypeptide isattached to an organic or inorganic chemical entity that has an anioniccharge, the C-terminus is an acid or an amide and the composition has apH of 6.0.

Another embodiment includes a pharmaceutical composition comprising apharmaceutically acceptable salt of an ShK polypeptide having theformulaArg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(SEQ ID NO:3); 10 mM sodium phosphate; 150 mM NaCl; and Polysorbate 20at 0.05 w/v %, wherein the ShK polypeptide is attached to an organic orinorganic chemical entity that has an anionic charge and the compositionhas a pH of 6.0.

Another embodiment includes a pharmaceutical composition comprising apharmaceutically acceptable salt of an ShK polypeptide having theformulap-phospho-Tyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(ShK-186; SEQ ID NO:2); 10 mM sodium phosphate; 150 mM NaCl; andPolysorbate 20 at 0.05 w/v % and wherein the composition has a pH of6.0.

Another embodiment includes a pharmaceutical composition comprising anShK polypeptide having the formulaTyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(ShK-198; SEQ ID NO:5); 10 mM sodium phosphate; 150 mM NaCl; andPolysorbate 20 at 0.05 w/v % and wherein the composition has a pH of6.0.

Embodiments disclosed herein also include units of manufacture forpharmaceutical use. One embodiment of such a unit of manufacturecomprises at least one glass vial prepared under sterile conditions thatcontains a pharmaceutical composition described herein. In anotherembodiment, the pharmaceutical composition within the glass vial isstable for at least six months at −70° C. In another embodiment, theunit of manufacture further comprises instructions for diluting andpreparing the pharmaceutical composition for administration to a human.

In another embodiment, the unit of manufacture for pharmaceutical usecomprises at least one sterile syringe containing a pharmaceuticalcomposition described herein. In another embodiment, the unit ofmanufacture further comprises instructions for administering thepharmaceutical composition to a human.

Embodiments disclosed herein also include methods of manufacturing thedescribed pharmaceutical compositions. One such embodiment includes aprocess for manufacturing a pharmaceutical composition comprising: (a)preparing a solution of 0.05% polysorbate 20 in an aqueous carrier at apredetermined concentration; (b) adding to the solution of step (a) apredetermined amount of a polypeptide having SEQ ID NO:1 or apharmaceutically acceptable salt thereof, wherein the C terminus is anacid or an amide, and wherein the polypeptide is attached to an organicor inorganic chemical entity that has an anionic charge; (c) adjustingthe pH of the solution of step (b) until the polypeptide dissolves inthe solution; and (d) if necessary, adjusting the pH of the solution ofstep (c) to a pH of 5-7, thereby manufacturing the pharmaceuticalcomposition.

Embodiments disclosed herein also include methods of preventing,treating or alleviating the symptoms of an autoimmune or metabolicdisorder. One embodiment includes administering a pharmaceuticalcomposition described herein to a human in need of such preventing,treating or alleviating of an autoimmune or metabolic disorder in anamount that is effective to prevent, treat or alleviate the symptoms.

In another embodiment, the disorder is an autoimmune disorder selectedfrom the group consisting of multiple sclerosis, type-1 diabetesmellitus, rheumatoid arthritis, psoriasis, inflammatory bowel disease,contact-mediated dermatitis, psoriatic arthritis, asthma, allergy,restinosis, systemic sclerosis, fibrosis, scleroderma,glomerulonephritis, Sjogren syndrome, inflammatory bone resorption,transplant rejection, graft-versus-host disease, and lupuserythematosis.

In another embodiment, the disorder is a metabolic disorder selectedfrom the group consisting of obesity, Type 2 diabetes,hypercholesterolemia, coronary artery disease, metabolic syndrome,metabolic syndrome X, insulin resistance, hyperlipidemia, lipodystrophy,dyslipidemia, hypertriglyceridemia, glucose intolerance, hypertension,overweightness, and disorders of energy metabolism.

In another embodiment, the pharmaceutical composition is administereddaily, weekly, monthly, every two months, every three months, or everysix months.

In another embodiment, the pharmaceutical composition is administeredsubcutaneously.

In a further embodiment, the ShK polypeptide is radiolabeled.

In one embodiment, the ShK polypeptide is labeled with ¹¹¹In.

In a further embodiment, the ShK polypeptide is ¹¹¹In-labeled ShK-221.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A-1F illustrate biodistribution studies with radiolabeled ShK inrat and squirrel monkey. ¹¹¹In-labelled ShK-221 was administered toSprague Dawley rats (100 μg/kg; 0.7 mCi) and squirrel monkey (35 μg/kg;0.84 mCi) as a single subcutaneous injection to the scapular region ofeach animal. SPECT and CT scans were collected continuously during thefirst hour (4×15 m intervals) and at 4, 8, 24, 48, 72, 120, and 160hours post-dose. Flattened 2D images of the 3D reconstructions are shownfor the 4, 24, 72 and 160 hour time points for monkey (FIG. 1A) and the1, 8 and 24 hour time points for rat (FIG. 1C). Both animals show slowabsorption of drug from the injection site and significant early andsustained distribution to kidney and to a lesser extent liver. Ratimages revealed significant radioactivity in bladder at 1 h, theduodenum and small intestine at 4 and 8 hours and adrenal glands at 8and 24 h. Kidney associated radioactivity in both species wasprincipally identified in the cortex (FIG. 1B and FIG. 1D).Quantification of ¹¹¹In-ShK-221 at the injection site in monkey (top)and rat (bottom) revealed a biphasic decay with an initial half-life ofapproximately 1-1.5 hours and a terminal half-life of >48 hours (FIG.1E). Drug concentrations in monkey (top) and rat (bottom) whole bloodfollowed a similar biphasic decay with an initial half-life ofapproximately 1.5 hours and a terminal half-life of >64 hours (FIG. 1F).Blood concentrations remained above the K_(d) for Kv1.3 throughout theentire study period and above the 80% saturation concentration (233 pM)through the first 120 hours consistent with a slow, continuousdistribution from the injection site throughout the study period.

FIGS. 2A-2C illustrate the development of a radiolabeled analog ofShK-186. Radiolabeling of ShK-186 was carried out by solid-phasecoupling of DOTA to the amino terminus of ShK-198 via a linker to formShK-221 (SEQ ID NO:6; FIG. 2A). Indium incorporation into the DOTA ringwas carried out by incubation at 95° C. in sodium acetate pH 5.Indium-labeled ShK-221 yielded a distinct migration pattern byion-exchange chromatography (FIG. 2B) with the resulting chelates havingthe expected mass (FIG. 2C).

FIGS. 3A and 3B show a comparison of the Kv1.3 channel-blocking potencyof ShK-186 and two labeled analogs, ShK-221-gadolinium (ShK-221-Gd) andShK-221-indium (ShK-221-In): (FIG. 3A) Representative whole-cell Kv1.3currents in the absence and presence of ShK-221-Gd. (FIG. 3B)Dose-response curve showing the effect of ShK-186, ShK-221-Gd andShK-221-In on Kv1.3 currents. Stable Kv1.3-transfected cell lines wereused for this study (Beeton, et al. Mol. Pharmacol. 67:1369-1381 (2005),incorporated by reference herein for its teachings regarding the same).Electrophysiological recordings were carried out in the whole-cellconfiguration of the patch-clamp technique as described (Beeton, et al.2005 and Wolff, H, et al., Proc. Natl. Acad. Sci. USA 97:8151-8156(2000), incorporated by reference herein for its teachings regarding thesame). The external solution was sodium Ringer and the pipette solutionwas KF (300 mOsm). Kv1.3 currents were elicited by 200-ms depolarizingpulses from a holding potential of −80 to 40 mV. ShK-186, ShK-221-Gd andShK-221-In were each tested at several concentrations. The reduction inpeak current at 40 mV for each concentration was used to generate adose-response curve using Origin software (OriginLab Corp., Northampton,Mass.). The IC₅₀ values were: ShK-186=68.99±4.01 pM (n=5),ShK-221-Gd=58.23±1.38 pM (n=5), and ShK-221-In=63.80±2.25 pM (n=3).

DETAILED DESCRIPTION

The present disclosure provides ShK-based pharmaceutical compositionsand methods of manufacturing and using the same. As used herein, theterm “ShK polypeptide” refers to all natural and synthetic ShKpolypeptides and their derivatives, analogs, and modifications ascontemplated herein. Such modifications and analogs include thepolypeptide of SEQ ID NO:1 to which an organic or inorganic chemicalentity that has an anionic charge is attached via anaminoethyloxyethyloxy-acetyl linker. As used herein, a “pharmaceuticalcomposition” comprises at least one ShK polypeptide disclosed hereintogether with one or more pharmaceutically acceptable carriers,excipients or diluents, as appropriate for the chosen mode ofadministration. The “at least one ShK polypeptide” can include bothnatural and synthetic ShK polypeptides.

As stated, many immune-related human diseases and metabolic disordersare attributed to the action of memory T cells. Two categories of memoryT cells are known: central memory T cells (T_(CM)) and effector memory Tcells (T_(EM)). Upon activation, T_(EM) cells up-regulate Kv1.3 K⁺ ionchannels. The antigen-driven proliferation of T_(EM) cells is sensitiveto Kv1.3 K⁺ ion channels blockers (Wulff et al., J. Clin. Invest.111:1703-1713, 2003), and the polypeptide ShK, originally isolated fromthe Caribbean sea anemone Stichodactyla helianthus, serves as such ablocker. By blocking Kv1.3 channels, ShK suppresses proliferation ofT_(EM) cells at picomolar concentrations.

Myelin-specific autoreactive T cells in MS patients are predominantlyactivated T_(EM) cells (Wulff et al., J. Clin. Invest. 111:1703-1713,2003), so although the compositions disclosed herein are not bound by aspecific mechanism, there is a sound basis for preparing Kv1.3 blockersas pharmaceutical compositions to reduce or eliminate activation ofT_(EM) cells in the treatment, prevention or alleviation of symptoms inmultiple sclerosis patients.

A native ShK polypeptide is described in, for example, Pennington, M. W.et al., Int. J. Pept. Protein Res. 46:354-358 (1995) which isincorporated by reference herein for its teachings regarding the same.Exemplary ShK structures that are within the scope of the presentdisclosure are also published in Beeton, C. et al., Targeting EffectorMemory T Cells with a Selective Peptide Inhibitor of Kv1.3 Channels forTherapy of Autoimmune Diseases, Molecular Pharmacology, Vol. 67:1369(2005), and in U.S. Pat. No. 8,080,523 (U.S. Patent Publication20080221024), all of which are incorporated herein by reference fortheir teachings regarding the same.

An exemplary polypeptide that forms the basis for the polypeptides usedin the compositions herein is shown in SEQ ID NO:1. In particularembodiments, the C-terminus is an acid (for example, COOH) or an amide(for example, CONH₂), and the polypeptide is attached to an organic orinorganic chemical entity that has an anionic charge. By “amide” it ismeant the substitution of the C-terminal hydroxyl group (OH) of an acidwith NH₂. Such substitution is designated herein using the term “amide,”or as the C-terminal amino acid-NH₂, as in “-Cys-NH₂.”

The safety, potency, and specificity of ShK has been investigated andattaching the polypeptide to an organic or inorganic chemical entitythat has an anionic charge has been shown to improve the suitability ofShK for use in pharmaceutical compositions.

Those skilled in the art are aware of techniques for designing ShKpolypeptides with enhanced properties, such as alanine scanning,rational design based on alignment mediated mutagenesis using known ShKpolypeptide sequences and/or molecular modeling. For example, ShKpolypeptides can be designed to remove protease cleavage sites (e.g.,trypsin cleavage sites at K or R residues and/or chymotrypsin cleavagesites at F, Y, or W residues) in a ShK polypeptide-containingcomposition.

A variety of modifications of the SEQ ID NO:1 polypeptide are suitable.A polypeptide can have any combination of the modifications disclosedherein. To improve the pharmacokinetic and pharmacodynamic (PK/PD)properties of the ShK structure, residues that are sensitive todegradation properties can be replaced or substituted. For example, theMet residue at position 21 can be substituted to impart a stabilizingeffect against oxidation. In one embodiment, the Met at position 21 issubstituted with Nle. Substitution of the C-terminal acid function withan amide can also impart stability. These two substitutions to theprimary structure of ShK can be combined with an anionic moiety at theN-terminus to produce a stable and selective Kv1.3 blocker. Accordingly,one embodiment disclosed herein includes SEQ ID NO:1 wherein themethionine at position 21 is substituted with Nle, an amide is presentat the C-terminus and/or an anionic moiety is present at the N-terminus.

Nonhydrolyzable phosphate substitutions also impart a stabilizing effecton the phosphate groups, as well as stability against phosphataseenzymes.

As stated, certain embodiments include the attachment of an organic orinorganic chemical entity. The site of attachment can be the N-terminus,(the first Arg in SEQ ID NO:1), but modifications are not limited toattachment at this site. Exemplary chemical entities can be attached byway of a linker, such as an aminoethyloxyethyloxy-acetyl linker(referred to herein interchangeably as Aeea or AEEAc), or by any othersuitable means.

Non-limiting examples of appropriate chemical entities includeL-Pmp(OH₂); D-Pmp(OH₂); D-Pmp(OHEt); Pmp(Et₂); D-Pmp(Et₂); L-Tyr;L-Tyr(PO₃H₂) (p-phospho-Tyrosine); L-Phe(p-NH₂); L-Phe(p-CO₂H);L-Aspartate; D-Aspartate; L-Glutamate; and D-Glutamate. Theabbreviations used are defined as follows: Pmp(p-phosphonomethyl-phenylalanine); and Ppa(p-phosphatityl-phenylalanine). Alternatives to PmP and Ppa include,without limitation, Pfp (p-Phosphono(difluoro-methyl)-Phenylalanine) andPkp (p-Phosphono-methylketo-Phenylalanine).

Non-limiting examples of chemical entity/linker combinations includeAEEAc-L-Pmp(OH₂); AEEAc-D-Pmp(OH₂); AEEAc-D-Pmp(OHEt); AEEAc-L-Pmp(Et₂);AEEAc-D-Pmp(Et₂); AEEAc-L-Tyr; AEEAc-L-Tyr(PO₃H₂); AEEAc-L-Phe(p-NH₂);AEEAc-L-Phe(p-CO₂H); AEEAc-L-Aspartate; AEEAc-D-Aspartate;AEEAc-L-Glutamate; and AEEAc-D-Glutamate. In the chemical entitiesgenerally, where the amino acid residue has a chiral center, the Dand/or L enantiomer of the amino acid residue can be used.

For use in the disclosed pharmaceutical compositions, ShK polypeptidecan be naturally occurring or synthetic or be provided as a mixture ofnaturally occurring and synthetic ShK.

The ShK polypeptide can be prepared as a salt. In an exemplary saltherein, the refolded polypeptide obtained from the RP-HPLC step(Example 1) can be returned to the column and eluted. Before drying,sodium or potassium acetate at 50 mM can be added to the proteinsolution. This step yields a salt form of the protein which is readilysoluble upon reconstitution from the dried form. In the exemplaryformulation used in the Examples (ShK-186), sodium acetate was added,and the acetate content of the formulation was 10.4% by weight, bychemical analysis. ShK-186 is a 37 amino acid synthetic peptidederivative of the Stichodactyla toxin. ShK-186 has also been referred toas SL5 in the literature and is identified by CAS Registry Number1081110-69-1.

For a polypeptide-containing composition to find use as a pharmaceuticalcomposition, it must meet several criteria in terms of stability,solubility, and pH, and preferably only contain materials consistentwith administration to animals including, without limitation, mammals,and particularly humans. The composition can be varied depending on themode of administration, such as subcutaneous, intravenous, etc.

Although some formulations of therapeutic ShK polypeptides are known inthe art (for example, Beeton, C. et al., referenced above; and U.S. Pat.No. 7,833,979), none have the stability and solubility of the ShK-basedpharmaceutical compositions disclosed herein. The stable and solubleShK-based pharmaceutical compositions disclosed herein were achievedthrough varying a number of factors including surfactant concentrations,pH, removal of components used in previous formulations and otherparameters described more fully in the Examples below.

One particular formulation with optimal stability and solubilityincludes:

TABLE 1 Pharmaceutical composition of P6N formulation ComponentConcentration Purpose ShK-186 polypeptide Up to 500 mg/mL Active agentSodium phosphate 10 mM Buffering agent NaCl 150 mM Tonicity modifierPolysorbate 20 0.05% (w/v) Surfactant pH of 6.0

Therapeutically and prophylactically effective amounts of the disclosedpharmaceutical compositions as well as dosage regimens for treating,preventing and/or alleviating symptoms of an autoimmune disorder ormetabolic disorder can be determined by an attending physician,considering various factors such as the age, condition, body weight, sexand diet of the patient, the severity of the condition being treated,time of administration, and other clinical factors. Generally, the dailyamount or regimen should be in the range of 1 to 10,000 micrograms (μg)of the ShK polypeptide per kilogram (kg) of body mass, in the range of 1to 5,000 μg per kilogram of body mass, in the range of 1 to 1,000 μg perkilogram of body mass or in the range of 1 to 100 μg per kilogram ofbody mass.

Pharmaceutical compositions disclosed herein can be used to treatautoimmune-related disorders such as multiple sclerosis, type-1 diabetesmellitus, rheumatoid arthritis, psoriasis, inflammatory bowel disease,contact-mediated dermatitis, psoriatic arthritis, asthma, allergy,restinosis, systemic sclerosis, fibrosis, scleroderma,glomerulonephritis, Sjogren syndrome, inflammatory bone resorption,transplant rejection, graft-versus-host disease, and lupus erythematosisand metabolic disorders such as obesity, Type 2 diabetes,hypercholesterolemia, coronary artery disease, metabolic syndrome,metabolic syndrome X, insulin resistance, hyperlipidemia, lipodystrophy,dyslipidemia, hypertriglyceridemia, glucose intolerance, hypertension,overweight, and disorders of energy metabolism.

For long-term storage of the pharmaceutical compositions, it can beuseful to store them in lyophilized form. The present disclosureencompasses such lyophilized pharmaceutical compositions including butnot limited to those prepared by the processes described below.

One process of lyophilizing can comprise the steps of: (a) lowering thetemperature of the pharmaceutical composition to −40° C.; (b) holdingthe temperature at −40° C. for a predetermined time; (c) raising thetemperature of the solution to 20° C.; (d) holding the temperature at20° C. for a predetermined time; and e) reducing the pressure in step(d) to a pressure suitable for lyophilization and holding thetemperature at 20° C. for a predetermined time, thereby lyophilizing thepharmaceutical composition.

In this process of lyophilization, step (a) can be performed within 2hours; step (b) can be performed within 3 hours; step (c) can beperformed over 13 hours and at a pressure of 110 μbar; step (d) can beperformed over 13 hours and at a pressure of 110 μbar; and step (e) canbe performed over 5 hours and the pressure is reduced to 10 μbar.

The process of lyophilizing the pharmaceutical composition can alsocomprise the steps of: (a) lowering the temperature of thepharmaceutical composition to −45° C.; (b) holding the temperature at−45° C. for a predetermined time; (c) raising the temperature of thesolution to −20° C.; (d) raising the temperature of the solution to 25°C.; and (e) holding the temperature at 25° C. for a predetermined time,thereby lyophilizing the pharmaceutical composition.

In this process, step (a) can be performed within 6 hours; step (b) canbe performed within 3 hours; step (c) can be performed over 19 hours andat a pressure of 150 μbar; step (d) can be performed over 13 hours andat a pressure of 150 μbar; and step (e) can be performed over 8 hoursand at a pressure of 150 μbar.

The lyophilized pharmaceutical composition can be contained withinpackaging material, and the packaging can further comprise instructionsfor reconstitution of the pharmaceutical composition for end-use by amedical professional, patient, or researcher.

The lyophilized pharmaceutical composition can have a water content ofless than 5%, less than 4%, or less than 3.5%.

As indicated in the Examples below, the pharmaceutical compositions canbe stored for several months at −70° C., −20° C., or 4° C., for examplein a sterile glass vial. A vial can contain 1 ml of composition P6N (seeTable 1) or another pharmaceutical composition disclosed herein, suchthat the vial will physically contain a solution of 50 mg ShKpolypeptide (in one embodiment as an acetate salt), dissolved in 10 mMsodium phosphate and 150 mM NaCl, with 0.05% (w/v) polysorbate 20, andwith the final pH adjusted to 6.0.

The vial can be further prepared as a unit of pharmaceuticalmanufacture, with one or more vials in a package that can also containor be printed with instructions for storage, and for diluting andadministering the pharmaceutical composition, for end-use by a medicalprofessional, patient, or researcher. A suitable mode of dilutingincludes the use of water for injection, referred to herein as WFI. Asuitable amount of diluent can be part of the unit of manufacture, forexample in its own sterile container with optional instructions for use.

The pharmaceutical composition can comprise 0.1, 0.5, 0.75, 1, 2, 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41,42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 or 55, or up to 500mg/ml of the ShK polypeptide or pharmaceutically acceptable salt thereofaccording to this disclosure. The precise concentration will depend onfactors within the control of the manufacturer and/or the end-user,depending upon desired dose and intended therapeutic or research use.The concentration also encompasses any and all intermediate numberswithin the above range, such as 1.5 mg/ml, 2.5 mg/ml, etc.

For administration of the pharmaceutical composition, a suitable routeis subcutaneous injection. A medical practitioner will be familiar withmethods of administration depending on the patient and the mode oftreatment, such as subcutaneous, intravenous, etc. U.S. Pat. No.7,918,824 discloses syringes suitable for patient use and isincorporated by reference herein for its teachings regarding the same.Intravenous administration is also contemplated. For example, pre-filledneedleless syringes, such as glass syringes, for use with needlelessintravenous access systems can be used. Also contemplated areimplantable devices for timed release of the pharmaceuticalcompositions. The compositions are not intended to be limited to anyparticular choice of administration.

The disclosure, for example, encompasses drawing the pharmaceuticalcomposition in liquid form, for example 0.5 cc, into a syringe, such asa Becton Dickinson (BD) Slip-Tip Sub-Q 1 cc syringe fitted with a 26G×⅝inch needle (BD Part #309597). One or more syringes can be incorporatedinto a unit of manufacture, including packaging and optionalinstructions for end-use by a medical professional, patient, orresearcher.

The pharmaceutical compositions can be made up in, without limitation, asolid form (including granules, powders or suppositories) or in a liquidform (e.g., solutions, suspensions, or emulsions). The pharmaceuticalcompositions can be subjected to conventional pharmaceutical operationssuch as sterilization and/or can contain conventional adjuvants, such aspreservatives, stabilizers, wetting agents, emulsifiers, buffers, etc.

Solid dosage forms for oral administration can include capsules,tablets, pills, powders, and granules. In such solid dosage forms, theactive ShK polypeptide can be admixed with at least one inert diluentsuch as sucrose, lactose, or starch. Such dosage forms can alsocomprise, as in normal practice, additional substances other than inertdiluents, e.g., lubricating agents such as magnesium stearate. In thecase of capsules, tablets, and pills, the dosage forms can also comprisebuffering agents. Tablets and pills can additionally be prepared withenteric coatings.

Liquid dosage forms for oral administration can include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups, and elixirscontaining inert diluents commonly used in the art, such as water. Suchcompositions can also comprise adjuvants, such as wetting, sweetening,flavoring, and perfuming agents. The pharmaceutical composition cancontain more than one embodiment of the present disclosure. Preparationsfor oral administration can be suitably formulated to give controlledrelease of the active ShK polypeptide.

For buccal administration the compositions can take the form of tabletsor lozenges formulated in conventional manner.

The ShK polypeptides can be formulated for parenteral administration byinjection, e.g., by bolus injection or infusion. Formulations forinjection can be presented in unit dosage form, e.g. in glass ampoule ormulti dose containers, e.g., glass vials. The compositions for injectioncan take such forms as suspensions, solutions or emulsions in oily oraqueous vehicles, and can contain formulatory agents such as suspending,stabilizing, preserving and/or dispersing agents. Alternatively, theactive ingredient can be in powder form for constitution with a suitablevehicle, e.g., sterile pyrogen-free water, before use.

In addition to the formulations described above, the ShK polypeptidescan also be formulated as a depot preparation. Such long actingformulations can be administered by implantation or by intramuscularinjection.

For nasal or pulmonary administration or any other administration byinhalation, the ShK polypeptides for use according to the presentdisclosure are conveniently delivered in the form of an aerosol spraypresentation for pressurized packs or a nebulizer, with the use ofsuitable propellant, e.g., dichlorodifluoromethane,trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide orother suitable gas or mixture of gases.

In a non-limiting example, a ShK polypeptide disclosed herein can belabeled using a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid(DOTA)-chelate of Indium-111 (In¹¹¹) or other radiolabeled metalconjugated to a tyrosine or phosphotyrosine moiety on the polypeptide.Such methods are described in, for example, Schultz, M. K. et al.,“Synthesis of a DOTA-Biotin Conjugate for Radionuclide Chelation viaCu-Free Click Chemistry,” Organic Letters 12:2398-2401 (2010) which isincorporated by reference herein for its teachings regarding the same.In an example suitable for diagnosis, such as by MRI, a ShK polypeptidedisclosed herein can be labeled using a DOTA-chelate of indium (In),gadolinium (Gd) or other paramagnetic ion. Other chelation orconjugation chemistries can also be used.

As described in Example 6 and illustrated in FIGS. 1A-3B, a radiolabeledanalog of ShK (ShK-221) was used to measure the total drug concentration(unbound plus bound) in whole blood. Previous studies suggest that only10% of the drug is available unbound in plasma (Chi et al., Toxicon59:529-546, 2011). This is consistent with the observation that at 1hour after administration of a 35 μg/kg dose of radiolabeled ShK-221 tosquirrel monkey, approximately 15 nM of drug was measured in wholeblood, suggesting an unbound fraction of ˜7% by this method. The freefraction of the drug may actually be lower in the rat compared tonon-human primates. At 1 hour post dose of 100 μg/kg in rats,approximately 14 nM of ShK-221 was observed in whole blood. This may bedue to the drug binding to other blood constituents such as platelets,which express Kv1.3 on their surface and have been found to be presentin exceedingly high numbers in rat whole blood (5-10× Human) (McCloskeyet al., J. Physiol. 588:1399-1406, 2010; Trowbridge et al., Clin. Phys.Physiol. Meas. 5:145-170, 1984).

The sensitive radiolabeling method allows the detection of a biphasicterminal elimination profile for ShK in rat and squirrel monkey speciescharacterized by a rapid initial phase and a very long terminal phase.The terminal half-life computed using ¹¹¹In-ShK-221 was >64 hours inmonkey with sustained blood levels above the K_(d) for 7 days. The bloodconcentrations mimic a biphasic (fast then slow) absorption from theinjection site. In summary, the biodistribution of radiolabeled ShK-221in rat and squirrel monkey is characterized by a very slow distributionfrom the injection site, significant concentrations of drug peripherallyin the injection site, kidney, and liver, and a long terminalelimination phase in whole blood. Drug levels remained above ˜200 pM inblood for approximately 7 days in the monkey and 3 days in the rat. Thedata in Example 1 provide one embodiment of the use of a radiolabeledShK polypeptide to study the distribution of the drug in vivo. DOTA isexemplified herein, but other metal chelators can be used, such as DTPA(diethylenetriaminepentaacetic acid). Thus, in addition to therapeuticuses, the ShK polypeptides disclosed herein can also be useful indiagnosing or monitoring diseases characterized by dysfunction of theirassociated protein of interest. In one embodiment, a method is providedfor detecting a protein of interest in a biological sample, such as areceptor or ion channel that is capable of being affected, comprisingthe steps of: (a) contacting the sample with a ShK polypeptide; and (b)detecting an effect on the protein of interest by the peptide. Thebiological samples include tissue specimens, intact cells, or extractsthereof. The compositions disclosed herein can be used as part of adiagnostic kit to detect the presence of their associated proteins ofinterest in a biological sample. Such kits can employ a compositiondisclosed herein and having an attached label to allow for detection.The peptides are useful for identifying normal or abnormal proteins ofinterest.

The Examples below describe the optimization of the methods disclosedherein. The Examples below are included to demonstrate particularembodiments of the disclosure. Those of ordinary skill in the art shouldrecognize in light of the present disclosure that many changes can bemade to the specific embodiments disclosed herein and still obtain alike or similar result without departing from the spirit and scope ofthe disclosure.

EXAMPLES Example 1 Synthesis of (pTyr)-AEEA-Arg-35-Cys-NH₂ (ShK-186)

Synthesis of the linear polypeptide precursor was carried out asfollows. The linear peptide was assembled on Rink Amide (MBNA) Rx (sub:0.4 mmol/g) and the following protecting groups were used for theFmoc-chemistry: Arg (Pbf), Ser (tBu), Cys (Trt), Asp (OtBu), Thr (tBu),Lys (Boc), Arg (Pbf), Gln (Trt), His (Trt), Tyr (tBu), and Tyr(P(OH)O₂Bzl). All amino acids were coupled by DIC/HOBt activation at ascale of 2 mmol using CS536 automated synthesizer. These parameters werescaled up to 200 mmol.

For the cleavage step, the DeFmoc peptide was finally cleaved from theresin by 4-hour treatment of Reagent ‘K’ [TFA/TIS/1,2-Ethanedithiol(EDT)/H₂O/Phenol (89/2/2/2/5)] at room temperature with stirring. (TISrefers to triisopropylsilane.) The ratio can be varied as long as thecleavage is accomplished, and phenol can be optionally eliminated. Inpreparations without phenol, the ratio of TFA/TIS/EDT/H₂O was, forexample, 47/1/1/1. The crude peptide was separated from the resin by SPEtube filtration and the resin was rinsed consecutively with TFA whichwas combined with the initial filtrate.

After evaporation of TFA solvents from the filtrate (to ⅕ volume oforiginal cleavage cocktail), the crude peptide was then precipitated byaddition of cool ethyl ether and dried in vacuum to give linearpolypeptide for further oxidation.

After linear crude polypeptide was dissolved in water to a concentrationof 0.3 mg/mL (changed slightly based on manufacture), NH₄OH was thenadded to execute oxidization at pH 8 (later batch records show lower (pH7-7.5)) for 30 hours. The completion of oxidization was checked by ESImass spectrum. Additionally, the HPLC analysis showed the conversion ofthe linear peptide to the oxidized form. The oxidation was acidified byTFA (or acetic acid) to (pH 2-3). Air oxidation is one method ofachieving disulfide bridge formation. Example 2 below shows analternative manner of obtaining the polypeptide with disulfide bonds.

For purification, the oxidized peptide was directly loaded and purifiedby RP-HPLC on a preparative C-18 column using acetonitrile as the mobilephase. Fractions with enough purity were combined and optionallylyophilized to give a white powder (ShK-186), 1.5 g (TFA salt).

A salt exchange step followed. The re-dissolved peptide (TFA salt) wasloaded on a prep C-18 column balanced by TEAP (triethylamine phosphate)20 mM. After 3× void volume washing with TEAP, the buffer was changed toNH₄OAc (50 mM). After 3× void volume washing of NH₄OAc and pH checking(pH 6-7), the buffer was changed to HOAc (0.5%). After washing 3× voidvolume of HOAc (0.5%) and pH checking (pH 2-3), a sharp gradient wasstarted to give the final polypeptide with acetate salt, 500 mg.

An optional purification step can be performed. The polypeptide can bepurified directly using an acetic acid system to give the finalpolypeptide with a higher yield. All of the individual steps in theabove process can be performed in batch to yield a larger overall scale.The final product can be lyophilized or maintained in solution.

Example 2 Preparation of ShK Polypeptides

Anionic amino acid residues can be attached to the N terminus of naturalor synthetic ShK polypeptide by way of a linker, such as anaminoethyloxyethyloxy-acetyl linker (Aeea), or by any other suitablemeans. Initially, Fmoc-Aeea-OH is coupled to the N-terminus of naturalof synthetic ShK toxin, for example by the method of Beeton, C. et al.,2005.

Either Fmoc-Tyr(PO₄Bzl)-OH, Fmoc-d-Tyr(PO₄Bzl)-OH, Fmoc-Tyr(PO₄Me₂)-OH,Fmoc-Pmp-OH, Fmoc-d-Pmp-OH, Fmoc-Pmp(Et)-OH, Fmoc-Pmp(Et)₂-OH,Fmoc-Tyr(tBu)-OH, or Fmoc-Amp(Boc)-OH is then coupled using DIC andHOBT.

The deblocked peptide resin is then cleaved and deprotected with ReagentK containing 5% triisopropylsilane for 2 hours at RT as described inKing, D. S. et al., Int. J. Peptide Protein Res. 36:255-266, 1990 whichis incorporated by reference herein for its teachings regarding thesame. Met(O) is reduced by addition of solid NH₄I to the cleavagecocktail at t-15 min. (Nicolas, E. et al., Tetrahedron 51:5701-5710,1995 which is incorporated by reference herein for its teachingsregarding the same). For the peptide containing Tyr(PO₄Me₂)-OH, acleavage cocktail containing 1 M TMSBr in TFA containing thioanisole asa scavenger for 18 hr at 4° C. is used (Tian, Z. et al., Int. J. PeptideProtein Res. 42:155-158, 1993 which is incorporated by reference hereinfor its teachings regarding the same). Incomplete removal of the methylprotecting groups is common when using this method and two of thespecies (Tyr(PO₄) and Tyr(PO₄Me)) are easily purified by RP-HPLC.

The Tyr(PO₄Me₂)-containing polypeptide is cleaved via standard Reagent Kcleavage keeping both Me groups intact. In each case, the cleavagemixture is filtered and the crude peptide is precipitated into ice-colddiethyl ether. The precipitate is collected, yielding approximately 75mg of peptide from 200 mg of resin. The crude product is dissolved in 20ml of 50% aqueous AcOH and diluted into 0.75 I of H₂O. The pH of thesolution is adjusted with NH₄OH to 8.2, and it was allowed to foldovernight with the addition of glutathione (2 mM:1 mM)(reduced:oxidized).

All polypeptides are purified using RP-HPLC as described in Pennington,M. et al., Int. J. Peptide Protein Res. 546:354-358, 1995; Pennington,M. et al., Biochemistry 35:16407-16411, 1996a; and Pennington, M. etal., Biochem. Biophys. Commun. 219:696-701, 1996b, each of which isincorporated by reference herein for its teachings regarding the same.Pure fractions are pooled and lyophilized. Each sample is confirmed byRP-HPLC, AAA (amino acid analysis) and MALDI-TOF MS and adjusted toaccount for peptide content prior to bioassay.

In the Examples below, the ShK polypeptide identified as ShK-186((phospho-Tyr)-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-GIn-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂,with amide at the C-terminus and with disulfide bonds betweenCys3-Cys35, Cys12-Cys28, and Cys17-Cys32) (SEQ ID NO:2) was prepared andchosen for identifying the components of a suitable pharmaceuticalcomposition; these components can be used for preparing pharmaceuticalcompositions comprising other ShK polypeptides, including but notlimited to ShK-198 and ShK-192 (CAS Registry Number 1159528-26-3).

Example 3 Surfactant Screening

In order to identify surfactant(s) for possible inclusion in thepharmaceutical compositions, the polypeptide is formulated in buffer, towhich test surfactants are added individually, and compared with sampleshaving no surfactant. Surfactants tested include polysorbate 20,polysorbate 80, and pluronic F68 at concentrations beginning with 0.01%.

To determine the effect of the surfactant, test samples and controls aresubjected to agitation or no agitation. Test samples and controls arethen analyzed by size-exclusion-HPLC (SEC-HPLC or SE-HPLC) to monitorchanges in characteristics, including soluble aggregation and loss ofmonomer recovery.

Using this method, ShK-186 polypeptide preparations were subject toconstant agitation for up to four hours at pH 5.8, in the presence ofpolysorbate 20 (0.01%), polysorbate 80 (0.01%), or pluronic F68 (0.10%)(Sigma-Aldrich). Surprisingly, all samples showed haziness withincreased turbidity, with or without surfactant. This suggested thatShK-186 was susceptible to agitation-induced precipitation.

Additional experimentation indicated that a non-typical concentration ofsurfactant protected the protein, and for subsequent experiments,polysorbate 20 at a concentration of 0.05% was used. In addition toincreasing the concentration of surfactant, lowering the pH from 5.8 to5.1 further improved the stability of ShK-186. The absence of solubleaggregation was confirmed by SEC-HPLC.

Example 4 Stability During Storage

Several parameters are tested in order to choose components of thepharmaceutical compositions that will protect the stability of thepolypeptide. According to the present method, these parameters are (pH4.0-7.0), buffer/solvent (10 mM Na acetate or 10 mM Na phosphate),stabilizer/solubilizer (NaCl 0.8%; sorbitol 5.0%; L-Arginine 3.0%),surfactant, storage and stress conditions (temperature, agitation,freeze/thaw, forced oxidation).

To study these parameters, samples of ShK-186 were dissolved in Naacetate or Na phosphate, and individual formulations were prepared asdescribed above. The peptides were then analyzed at time zero usingreversed-phase HPLC (RP-HPLC), ion-exchange HPLC (IE or IEX-HPLC), andsize-exclusion HPLC (SE-HPLC). Additional analysis was performed attwo-week, four-week, and eight-week time points. The evaluation of theformulations included monitoring drug concentration, visualinspection/turbidity, and checking pH over time at 10 and 25 mg/mL.

At time zero, the samples showed similar SE-HPLC chromatographs, exceptfor the sample prepared in phosphate buffer with arginine, pH 7.

At week two, the formulation containing arginine showed a turbidsolution with precipitates. This result was unexpected, as arginine hasbeen used to enhance the solubility of other protein products. Similarsolubility issues were observed at other temperatures, so thearginine-containing formulation was excluded from further analyses. Atfour weeks, SE-HPLC analysis showed that all remaining formulationsshowed no sign of soluble aggregate or cleavage at temperatures below25° C.

At week eight, all but one of the formulations showed good stabilityduring storage at −70° C.

Results from the full analysis at week eight led to the selection of aformulation referred to herein as “P6N” for providing the best stabilityin terms of recovery and degradation as observed by RP-HPLC, IE-HPLC,and SE-HPLC. This formulation, at pH 6, contains 10 mM Na acetate asbuffer; 0.8% NaCl as stabilizer/tonicity modifier; 0.05% polysorbate 20as surfactant; and a concentration of protein 11.2 mg/mL as determinedby RP-HPLC. The concentration of protein could be increased to 50 mg/mL.

The P6N formulation showed no sign of change after five cycles offreeze-thawing, as determined by RP-HPLC and IEX-HPLC. After three hoursof vigorous vortex stress, this formulation remained clear with no signof degradation, as determined using RP-HPLC and IE-HPLC.

Example 5 Stability of Clinical Formulation

The short-term stability of ShK-186 formulated in P6N is studied inthree sets of conditions designed to replicate clinical use: 72-hourstorage at variable temperatures, and 24-hour storage in sterile plasticsyringes. Long-term stability is tested over 1, 3, 6 and 12 months ofstorage at refrigerated (such as 5° C.) and freezing (such as −70° C.,−20° C.) temperatures.

For short-term studies, ShK-186 is diluted to a final concentration of 1mg/ml using either 5% (w/v) dextrose or 0.9% (w/v) saline, or WFIsolutions. A short-term stability study spans 72 hours of storage atrefrigerated (such as 5° C.) and elevated (such as 40° C.) temperaturesin each diluent. ShK-186 diluted in WFI, without preservatives, servesas a control. For long-term studies, ShK-186 is formulated in P6N ateither 25 or 50 mg/ml, then aliquots are used to prepare samples havinga final concentration as indicated, in mg/ml. Experimental parametersare shown in Tables 2 and 3.

TABLE 2 Diluent Stability Study, short term Final ShK-186 Storage Timeconcentration, temperature, points, mg/ml Diluent centigrade in hours 15% (w/v) Dextrose in WFI 5, 25, 40 0, 24, 72 1 0.9% (w/v) NaCl in WFI 1WFI (control)

TABLE 3 Diluent Stability Study, long term Final ShK-186 Storage Timeconcentration, Buffer, Stabilizer, temperature, points, mg/ml pH 10 mMw/v centigrade in months 25 6.0 Na 0.8% NaCl −70, −20, +5 0, 1, 3, 6,phosphate 12 10 6.0 Na 0.8% NaCl phosphate

A stability study performed at six months as shown in Table 3 yieldedthe following results based on SEC-HPLC and RP-HPLC. There was nosignificant change in pH or concentration at six months, compared toearlier time points. The overall results indicated that peptideconcentrations did not show any significant impact on stability offormulations. Stability at 5° C. showed a very slight drop compared to−20° C. and −70° C. Such results are consistent with the industrystandard of storing polypeptide pharmaceutical compositions at lowtemperatures, at least below freezing.

The stability in a delivery device such as a sterile plastic 1 ccsyringe is characterized. Such a device is suitable for subcutaneousdelivery. An exemplary, non-limiting device is a Becton Dickinson (BD)Slip-Tip Sub-Q 1 cc syringe fitted with a 26G×⅝ inch needle (BD Part#309597). 0.5 ml aliquots of ShK-186 formulation in diluents andconcentration shown in Table 2 are drawn and incubated in the syringe atambient conditions. Stability is tested over time reflecting clinicaluse, for example at four hours.

The stability of ShK-186 at three concentrations, 10, 25, and 50 mg/ml,under refrigerated and frozen storage temperatures is determined.Lyophilized ShK-186 is dissolved in P6N formulation to achieve thesefinal concentrations of ShK-186. Each formulated solution is sterilizedwith 0.2 μm filters, and transferred into suitable sterile vials, suchas type I borosilicate glass 3 cc vials at a fill volume of 0.5 ml pervial, under sterile conditions. The vials are stored at 5° C., −20° C.,and −70° C. for testing at time points of zero, three and six months.

The samples are tested at the designated time points using theparameters shown in Table 4.

TABLE 4 Analytical Methods to Monitor ShK-186 Stability Analyticalmethod Evaluation result Visual inspection Appearance pH pH valueOsmolality Osmolality value UV-Vis spectrophotometry Concentration (Abs280 mm) Turbidity (Abs 500-700 nm) Size exclusion HPLC Purity,aggregates, cleavage Reversed phase HPLC Purity, chemical modificationsBioassay Potency/strength of polypeptide

Summary The Examples above provide methods for determining suitablecomponents and conditions for preparing pharmaceutically acceptablecompositions comprising a ShK polypeptide for therapeutic use. Thevalidity of the methods was demonstrated by the successful preparationof ShK-186 in a formulation that provides for good solubility, long-termstorage (six months), and stability.

Example 6 Twelve Month Stability Study

SkH-186 was formulated at 10 mg/ml and 25 mg/ml in 10 mM SodiumPhosphate, pH 6.0, containing 0.8% NaCl and 0.05% Polysorbate 20, andincubated for 12 months at 5° C., −20° C., and −70° C. SE-HPLC analysisindicated that the concentration of the formulations did not have anyobvious impact on their stability. Incubation temperature had a slightimpact on the stability of both formulations. Samples incubated at 5° C.revealed a small increase in % HMV (1.19%) compared to frozen samples(0.95%). The percentage of LMW species remained relatively unchanged forboth formulations at all temperatures. Based on SE-HPLC results, theoverall percentage of monomer for both formulations at the end of thestudy was about 98%.

RP-HPLC analysis of the samples also indicated that the concentration offormulations did not have any obvious impact on the stability offormulations. Samples incubated at 5° C. revealed a slight increase inpre- and post-peak degradations (0.8-0.9%) compared to frozenformulations (0.3-0.7%). The data indicated that the higher incubationtemperature resulted in a higher percentage of post-peak degradationcompared to pre-peak degradation. Based on RP-HPLC results, the overallpurity for both formulations at the end of the study was about 99%.

Table 5 shows a summary of pH and concentration data collectedthroughout the timeframe of the 12-month study. At Time Zero, the valueswere as follows: for 10P6N (ShK-186 at 10 mg/mL), the pH was 6.1,Concentration (Conc, mg/mL) was 9.9 mg/mL, and Osmolality in mOsmo was317. For 25P6N (ShK-186 at 25 mg/mL), the pH was 6.0, Concentration was25.1 mg/mL, and Osmolality was 293. Based on the results, the pH andconcentration of samples remained relatively unchanged throughout thestudy regardless of incubation temperature.

TABLE 5 pH and Concentration of Formulations at 1, 3, 6 and 12 Months 1Month 3 Months 6 Months 12 months Sample ID Incubation Temp pH Conc pHConc pH Conc pH Conc 10P6N  5° C. 6.03 9.63 6.03 9.63 6.06 9.85 6.0710.2 10P6N −20° C. 6.03 9.54 6.03 9.54 6.07 9.94 6.10 9.96 10P6N −70° C.6.05 9.85 6.05 9.85 6.09 9.77 6.09 10.1 25P6N  5° C. 6.00 24.72 6.0025.78 6.04 25.08 6.06 25.8 25P6N −20° C. 6.00 24.76 6.00 25.31 6.0524.34 6.05 24.97 25P6N −70° C. 5.98 24.35 5.98 25.53 6.05 24.85 6.0923.71

Example 7 Biodistribution of Radiolabeled ShK-221

Introduction. In order to enhance the sensitivity of in vivo studies,measure the biodistribution of ShK-186, and evaluate the total (boundplus unbound) drug concentration in whole blood, a radiolabeled analogof ShK-186 was prepared and studied in two in vivo animal models, ratand squirrel monkey. In this Example, the term “ADME” refers toabsorption, distribution, metabolism, excretion.

Methods.

Animals. Sprague Dawley [Crl:CD®SD] rats (6-9 weeks old) were purchasedfrom Charles River Laboratories (Wilmington, Mass., USA) and housed in atemperature (64-79° C.) and humidity (30-70%) controlled facility. Foodand water were ad libitum.

Non-naïve squirrel monkeys (Saimiri boliviensis) were between 2 and 5years of age and were transferred from the MPI Research (Mattawan,Mich., USA) stock colony. The squirrel monkey was of Bolivian origin andprovided by the University of Texas MD Anderson Cancer Center (Houston,Tex. USA). Animals were housed individually in stainless steel cages inan environmentally controlled room. The monkeys were providedenvironmental enrichment; fluorescent lighting was provided 12 hours perday. Temperature was maintained between 64 and 84° C.; humidity was30-70%. Animals were provided Certified Primate Diet (PMI NutritionInternational, Inc., St. Louis, Mo., USA) twice daily. Primatreats® andother enrichment foods were provided on a regular basis. Water wasavailable ad libitum.

DOTA-conjugate of ShK-186 (ShK-221). “DOTA” refers to1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid. ShK-221 (MW4442) was synthesized using an Fmoc-tBu solid-phase strategy. Briefly,the peptide was assembled using a Chem-Matrix amide resin at a 0.2 mmolscale. All of the coupling steps were mediated with 6-CI-HOBt(N-Hydroxybenzotriazole) in the presence of diisopropyl carbodiimide.Fmoc removal was facilitated with 20% piperidine in DMF(dimethylformamide) containing 0.1 M HOBt to buffer the piperidine andminimize potential racemization at the 6 Cys residues. The DOTA(tBu)3-OHwas coupled to the N-terminus using the same aforementioned couplingprotocol. Following assembly, the peptide was cleaved from the resin andsimultaneously deprotected using a TFA (trifluoroacetic acid) cleavagecocktail Reagent K containing aromatic cationic scavengers for 2 hr atroom temperature. The crude peptide was filtered from the spent resinand subsequently isolated by precipitation into ice cold diethyl ether.The crude peptide was dissolved in 50% acetic acid and subsequentlydiluted into 3 L of H₂O containing 0.1 mM GSSG and 0.2 mM GSH. The pH ofthis peptide solution was adjusted to 8.0 with NH₄OH and allowed toslowly stir overnight. ShK spontaneously folds to a majorthermodynamically favored isomer which is the biologically active formof the peptide. The folded peptide was loaded onto a preparative RP-HPLCcolumn and purified using a gradient of MeCN versus H₂O containing 0.05%TFA. The fractions containing the desired peptide purity were pooledtogether and lyophilized. The final yield was 35 mg from a 0.2 mmolsynthesis; based upon starting resin this represents a yield of 8%.

SPECT/CT scanning of radiolabeled ShK-221. ShK-221 (100 μg) wasradiolabelled with 2 mCi ¹¹¹Indium chloride (GE Healthcare, ArlingtonHeights, Ill. USA) in a 300 μL reaction containing 50 mM sodium acetate,pH 5.0 for 30 min at 95° C. The reaction was quenched by the addition ofEDTA to a final concentration of 50 mM, and the radiolabeling efficiencywas assessed by reverse-phase HPLC (Luna 5 μC18(2) 100 A 250×4.6 mmcolumn, Phenomenex, Torrance, Calif. USA) on an Agilent 1100 systemusing an IN/US Systems Gamma RAM Model 4 radio-HPLC detector (LabLogicSystems, Brandon, Fla. USA). The labeling efficiency varied from 89-98%by this method. SPECT/CT scanning (NanoSPECT/CT Preclinical Imager,Mediso, Budapest, Hungary) was carried out on anesthetized animals infour 15 minute scans during the first hour and one scan each at 4, 8,24, 48, 72, 120 and 160 hours post dose. The individual projection frametime for each helical SPECT was set such that the duration of each scanwould last for approximately 15 to 45 minutes (varying by time-point toaccount for isotope decay) and allow for significant collection ofstatistics within each frame. The characteristic peaks detected from thespectra for ¹¹¹In were 245 and 171 keV (primary and secondary,respectively). The resulting projection data were reconstructed aftereach scan using an iterative model that takes advantage of the pinholegeometry to achieve a resolution of approximately 2 mm.

Approximately 10 μL blood samples were collected after each scan and theamount of radioactivity in the sample was measured using a Wallac Wizard1470 scintillation counter (Perkin Elmer, Waltham, Mass. USA). Drugconcentrations were computed by taking account of the specific activityof the administered dose, the half-life of ¹¹¹In (67.3 hours) and thecounting efficiency of the instrument.

Statistical and computational analysis. Statistical analysis was carriedout using the paired t-test. Goodness of model fit was determined usingthe R² statistic. Pharmacokinetic calculations were as follows: C_(max)and T_(max) were as observed in the dataset. AUC was computed using alinear trapezoidal method. The terminal elimination half-life wascomputed from the slope of the regression with the best adjusted R²value. AUC_(t-∞) was calculated by dividing the last observed drugconcentration by the terminal elimination slope.

Results of ADME studies with a radiolabeled analog of ShK-186. ShK-186contains a single iodinatable tyrosine at position 23. However, iodineincorporation into the ring, which is predicted to interact within thepore region of the Kv1.3 channel (Pennington et al., Biochemistry35:16407-16411, 1996), results in disruption of the channel bindingproperties of the drug. The amino terminus of ShK-198 was thereforemodified with a six-carbon linker attached via a peptide bond to one ofthe carboxylic acids of a DOTA chelate (FIG. 2A). The DOTA-conjugate,designated ShK-221, was readily coordinated with indium or gadolinium(FIGS. 2B-2C) and retained the full activity of the parent molecule(FIGS. 3A-3B). ¹¹¹In-labeled ShK-221 was prepared and administered bysubcutaneous injection to Sprague Dawley rat (1.0 mCi, 100 μg/kg) andsquirrel monkey (0.83 mCi, 35 μg/kg). The radiolabeling efficiencyranged from 89-98% over the series of experiments as determined by HPLC.Biodistribution of radiolabeled ShK-221 was evaluated by SPECT imagingcontinuously for the first hour post-dose, and then at 4, 8, 24, 48, 72,120, and 160 h. Background levels in the detection system wereapproximately 0.1 μCi/m³ (˜5 ng/m³ of ShK-221 at the initial time pointand 26 ng/m³ at the last time point). Blood samples were collectedfollowing each scan, and total radioactivity in whole blood was measuredby scintillation counting. Computed tomography was performed at eachtime point to enable colocalization of the radiolabel with keyanatomical structures.

Biodistribution of ¹¹¹In-ShK-221 in the squirrel monkey wascharacterized principally by slow absorption from the injection siteover the entire 160 hour period (FIGS. 1A and 1E). The quantity of drugpresent at the injection site followed a biphasic exponential decay(R²=0.95) with an initial half-life of approximately 1-1.5 hours and aterminal half-life of >48 hours (FIG. 1E). During the first hour,significant radioactivity could be observed in the kidney, increasing inintensity through 1 hour (˜1% injected dose (ID)/g, Table 1) and slowlydeclining to approximately baseline by 48 hours. Radioactivity in themonkey kidney was primarily observed in the cortical and medullaryregions during all time points and was comparatively absent in the renalpelvis except for the first hour (FIG. 1B). Significant bladderassociated radioactivity (T_(max)=0.75-1 h, 0.34% ID/g) was onlyobserved during the first four hours, after which relatively littleradiolabel was detected in bladder. No other organ showed significantlevels of radioactivity except for liver, which peaked at 0.75-1 hourpost dose administration (0.166% ID/g). Muscle, heart and brain all had<0.1% ID/g at all time points (Table 6).

TABLE 6 Maximum concentration of ¹¹¹In-ShK-221 in specific tissues ofsquirrel monkey following a 35 μg/kg subcutaneous injection Maximum ScanMaximum Tissue Period (h) (% injected dose/g) Injection Site    0-0.2517.3 Kidneys 0.75-1.0 0.976 Bladder 0.75-1.0 0.338 Liver 0.75-1.0 0.166Heart 0.75-1.0 0.093 Muscle  0.5-0.75 0.039 Brain 0.75-1.0 0.020

Biodistribution of ¹¹¹In-ShK-221 in the rat was similar to monkey andcharacterized by slightly faster absorption from the injection site andexcretion through the urine over the first 24 hours (FIGS. 1C and 1E).Significant radioactive label was observed in rat bladder (9.4% ID/g),kidney (2.9% ID/g) and liver (0.4% ID/g) during the first hour (FIG.1C). While little label was identified in the bladder at later timepoints, the amount of drug in liver and kidney was relatively constantthrough the first 24 h. Cross-sectional views of the rat kidney showedthat, with the exception of the first hour, radioactivity wasconcentrated primarily in the cortical regions similar to the monkey(FIG. 1D).

Evaluation of blood-associated radioactivity in monkey at each timepoint also demonstrated a biphasic exponential decay (R²=0.99) with aninitial half-life of approximately 1 hour and a terminal half-lifeof >64 hours (FIG. 1F). In monkey, much of the terminal eliminationphase was reflected by blood concentrations below the level ofquantitation of previous methods but well above the K_(d) for ShK-186.80% of the Kv1.3 channels in whole blood would be expected to be boundby drug through approximately 5 days post-dose, and concentrationsremain above the K_(d) for the entire 160 hour period.

The whole blood-associated radioactivity in the rat also showed abiphasic exponential decay (R²=0.99) with an initial half-life ofapproximately 1.7 hours and a terminal half-life of >72 hours (FIG. 1F).The drug concentrations, like the monkey, were well above the K_(d) forShK-186 until 5 days post dose. 80% of the Kv1.3 channels in whole bloodwould be expected to be bound by drug approximately 3-5 days post-dose.

The data show that biodistribution of radiolabeled ShK-221 in rat andsquirrel monkey is characterized by a very slow distribution from theinjection site, significant concentrations of drug peripherally in theinjection site, kidney, and liver and a long terminal elimination phasein whole blood. Drug levels remained above ˜200 pM in blood forapproximately 7 days in the monkey and 3 days in the rat.

Significant amounts of radioactivity were observed in the bladder ofboth rat (˜17% injected dose) and monkey (˜1% injected dose) at theearliest time points following administration of ¹¹¹In-ShK-221,suggesting that glomerular filtration is the principal eliminationpathway for the peptide shortly after injection. The large amount ofdrug excreted by the rat in the first hour is most likely a reflectionof the increased metabolism of the rat compared to the monkey. Following1 hour in rat and approximately 4 hours in monkey, little radioactivitywas observed in bladder whereas significant amounts of radioactivitywere still observed in the kidney cortex. Cortical concentration hasbeen reported for numerous radiolabeled versions of peptide drugsincluding octreotide, bombesin, exendin, and gastrin (Gotthardt et al.,J. Nucl. Med. 48:596-601, 2007). The mechanism of cortical retention hasbeen most thoroughly described for octreotide. Tubular reabsorption ofthe cationic octapeptide is mediated by megalin, a scavenger receptorexpressed in the proximal kidney tubule (de Jong et al., J. Nucl. Med.46:1696-1700, 2005). Mice with a kidney-specific disruption of thereceptor lack the cortical retention of radiolabeled octreotide seen inwild-type mice. Renal uptake of octreotide is partially mediated bycharge and can be disrupted by co-infusion of the positively chargedamino acids L-lysine and L-arginine (Bodei et al., Eur. J. Nucl. Med.Mol. Imaging 30:207-216, 2003). ShK-186 carries a net+6 charge atphysiological pH, and so its cortical retention may be mediated by asimilar mechanism.

In summary, ADME studies with radiolabeled ShK suggest that a singledose of drug can provide therapeutically meaningful blood concentrationsfor up to 5 days in rat and 7 days in monkey. These observations arerelevant to the clinical development of ShK-based peptide therapeutics,including ShK-186, since an optimized dose frequency will ensuretherapeutic efficacy, improve patient compliance, and reduce thepotential for drug accumulation during chronic administration.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe specification and attached claims are approximations that can varydepending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

The terms “a,” “an,” “the” and similar referents used in the context ofdescribing the invention (especially in the context of the followingclaims) are to be construed to cover both the singular and the plural,unless otherwise indicated herein or clearly contradicted by context.Recitation of ranges of values herein is merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range. Unless otherwise indicated herein, eachindividual value is incorporated into the specification as if it wereindividually recited herein. All methods disclosed herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention otherwise claimed. No languagein the specification should be construed as indicating any non-claimedelement essential to the practice of the invention.

Groupings of alternative elements or embodiments of the inventiondisclosed herein are not to be construed as limitations. Each groupmember can be referred to and claimed individually or in any combinationwith other members of the group or other elements found herein. It isanticipated that one or more members of a group can be included in, ordeleted from, a group for reasons of convenience and/or patentability.When any such inclusion or deletion occurs, the specification is deemedto contain the group as modified thus fulfilling the written descriptionof all Markush groups used in the appended claims.

Certain embodiments of this invention are disclosed herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations on these described embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than specifically disclosed herein. Accordingly,this invention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

Specific embodiments disclosed herein can be further limited in theclaims using consisting of or and consisting essentially of language.When used in the claims, whether as filed or added per amendment, thetransition term “consisting of” excludes any element, step, oringredient not specified in the claims. The transition term “consistingessentially of” limits the scope of a claim to the specified materialsor steps and those that do not materially affect the basic and novelcharacteristic(s). Embodiments of the invention so claimed areinherently or expressly described and enabled herein.

In closing, it is to be understood that the embodiments of the inventiondisclosed herein are illustrative of the principles of the presentinvention. Other modifications that can be employed are within the scopeof the invention. Thus, by way of example, but not of limitation,alternative configurations of the present invention can be utilized inaccordance with the teachings herein. Accordingly, the present inventionis not limited to that precisely as shown and described.

What is claimed is:
 1. A pharmaceutical composition suitable fordiagnostic in vivo use comprising a pharmaceutically acceptable salt ofa ShK polypeptide having the sequenceArg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys(SEQ ID NO:1) wherein the ShK polypeptide is attached to a detectablelabel and an organic or inorganic chemical entity that has an anioniccharge, and wherein the C-terminus is an acid or an amide.
 2. Thecomposition of claim 1 wherein said detectable label is a chelate ofIndium-111 (In¹¹¹).
 3. The composition of claim 2 wherein saiddetectable label is a1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-chelateof Indium-111 (In¹¹¹).
 4. The composition of claim 1 wherein saiddetectable label is a chelate of gadolinium (Gd).
 5. The composition ofclaim 4 wherein said detectable label is a DOTA-chelate of gadolinium(Gd).
 6. The composition of claim 1 wherein said ShK polypeptide has thesequenceTyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH₂(SEQ ID NO: 5) and the detectable label is at the amino terminus.
 7. Thecomposition of claim 6 wherein the detectable label is a1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-chelateof Indium-111 (In¹¹¹).